1. Field of the Invention
The present invention relates to task chairs, and in particular, to a ride mechanism for a task chair, the ride mechanism including an adjustable tension assembly.
2. Description of the Related Art
Task chairs are commonly used by persons while working in a seated position in an office or other occupational environment. Typically, such chairs include a base assembly with caster wheels for rolling movement over a floor surface, a pneumatic cylinder connecting the base assembly to the seat assembly for vertical adjustment, as well as a number of manual adjustment features to allow the user to adjust the movement characteristics of the chair to a desired configuration.
Some known task chairs include a backrest and a seat which are coupled to one another for synchronized movement such that, upon recline of the backrest responsive to reclining movement of a seated user, the seat moves forwardly and a rear portion of the seat moves downwardly. A disadvantage of this arrangement is that, upon reclining movement of the seated user, the user is moved slightly downwardly and away from a desk or other work surface near which the user is seated, and the user's line of sight is also shifted downwardly, requiring the user to adjust their head position to maintain a line of sight to a computer monitor, for example.
Known task chairs additionally include tension assemblies for providing a restoring force to the backrest of the chair, which force tends to bias the backrest into an upright position and to provide a resistance force against reclining of the backrest. Such mechanisms typically include a box-shaped control housing mounted beneath the seat in which a coil spring is mounted. Typically, the coil spring must be large in size to provide adequate resistance, requiring the control housing to take up a large amount of space beneath the seat. Also, the adjustment mechanism for varying the tension of the coil spring typically requires a large number of mechanical components contained within the control housing, increasing the difficulty of manufacture of the chair, the overall cost of the chair, and the overall weight of the chair. Further, manual adjustment of existing tension mechanisms is often confusing and tedious for the user, often requiring a user to rotate an adjustment knob over a very large number of turns.
What is needed is a task chair which includes a ride mechanism with a tension assembly which is an improvement over the foregoing.